htop

Overview

The htop command is an interactive process viewer and system monitor. It’s an enhanced version of top with a more user-friendly interface and additional features.

Syntax

htop [options]

Common Options

Option	Description
-d delay	Update delay in seconds
-u user	Show only user’s processes
-p pid	Show only specific PIDs
-s column	Sort by column
-C	No color mode
-h	Show help
--tree	Show process tree

Interactive Keys

Key	Action
F1	Help
F2	Setup
F3	Search
F4	Filter
F5	Tree view
F6	Sort by
F7	Nice -
F8	Nice +
F9	Kill
F10	Quit
Space	Tag process
U	Untag all
t	Tree mode
H	Hide/show threads

Display Information

Column	Description
PID	Process ID
USER	Process owner
PRI	Priority
NI	Nice value
VIRT	Virtual memory
RES	Resident memory
SHR	Shared memory
S	Process state
%CPU	CPU usage
%MEM	Memory usage
TIME+	CPU time
COMMAND	Command line

Key Use Cases

1. Monitor system performance
2. Identify resource-heavy processes
3. Kill problematic processes
4. Analyze memory usage
5. Track CPU utilization

Examples with Explanations

Example 1: Basic Usage

htop

Launches interactive process monitor

Example 2: Show Specific User

htop -u apache

Shows only apache user’s processes

Example 3: Tree View

htop --tree

Displays processes in tree format

Process Management

1. Kill process: Select and press F9
2. Change priority: F7 (decrease) or F8 (increase)
3. Search processes: F3
4. Filter processes: F4
5. Tag multiple processes: Space

System Information Display

Top panel shows: - CPU usage per core - Memory usage (RAM/Swap) - Load averages - Uptime - Task counts

Customization Options

1. Setup menu (F2):
   • Display options
   • Colors
   • Columns
   • Meters
2. Column configuration:
   • Add/remove columns
   • Reorder columns
   • Change column width

Common Usage Patterns

1. Find memory hogs:
   • Sort by %MEM (F6 → M)
   • Look for high RES values
2. Find CPU intensive processes:
   • Sort by %CPU (F6 → P)
   • Monitor over time
3. Process tree analysis:
   • Enable tree view (F5)
   • Expand/collapse with +/-

Performance Analysis

• Real-time updates
• Low system overhead
• Efficient display
• Responsive interface
• Minimal CPU usage

Related Commands

• top - Basic process monitor
• ps - Process snapshot
• pstree - Process tree
• iotop - I/O monitoring
• nethogs - Network usage

Additional Resources

• Htop Manual
• Process Monitoring Guide

Best Practices

1. Use tree view for process relationships
2. Monitor trends over time
3. Use filtering for specific analysis
4. Customize display for your needs
5. Learn keyboard shortcuts

Advanced Features

1. Strace integration:
   • Select process and press ‘s’
2. Lsof integration:
   • Select process and press ‘l’
3. Process following:
   • Follow process children

Installation

Most distributions include htop:

# Ubuntu/Debian
sudo apt install htop

# CentOS/RHEL
sudo yum install htop

# Arch Linux
sudo pacman -S htop

Configuration

Config file location: ~/.config/htop/htoprc - Saves display preferences - Column configurations - Color schemes - Sort preferences

Troubleshooting

1. Permission issues for some processes
2. High refresh rate impact
3. Terminal compatibility
4. Color display problems
5. Memory usage of htop itself

Comparison with top

Advantages over top: - Color display - Mouse support - Easier navigation - Better process tree - More intuitive interface - Horizontal scrolling

Integration Examples

1. With scripts:

   htop -d 1 -p $(pgrep firefox)

2. Remote monitoring:

   ssh server htop

3. Automated screenshots:

   htop -C > process_snapshot.txt